The bus boycott lasted more than a year. Many people tried to get King to end the boycott by threatening him.

King and the boycotters finally won. On November 13, 1956, the U.S. Supreme Court in Washington, D.C., agreed that Alabama's bus segregation laws were unconstitutional. (Unconstitutional means that the laws did not follow the U.S. Constitution and had to be struck down.)
Because the U.S. Supreme Court made the decision, all states had to follow the ruling. King celebrated by riding the bus seated next to a white man.